LocalMessageSender.SendAsync Method (String, Object)
Microsoft Silverlight will reach end of support after October 2021. Learn more.
Sends the specified messages to the configured receiver asynchronously.
Namespace: System.Windows.Messaging
Assembly: System.Windows (in System.Windows.dll)
Syntax
'Declaration
<SecuritySafeCriticalAttribute> _
Public Sub SendAsync ( _
message As String, _
userState As Object _
)
[SecuritySafeCriticalAttribute]
public void SendAsync(
string message,
Object userState
)
Parameters
- message
Type: System.String
The message to send.
- userState
Type: System.Object
A unique user-state object that functions as a task ID for the message transfer.
Exceptions
| Exception | Condition |
|---|---|
| ArgumentNullException | message is nulla null reference (Nothing in Visual Basic). |
| ArgumentException | message is longer than 40,960 characters. |
Remarks
You can send messages up to 40 kilobytes long.
When you call this method, the MessageReceived event occurs for the LocalMessageReceiver that corresponds to the ReceiverName and ReceiverDomain settings. Then, the SendCompleted event occurs, regardless of whether the message was successfully sent. You can retrieve the userState object in the SendCompleted event handler in order to identify the message.
For more information, see Communication Between Local Silverlight-Based Applications.
Examples
The following code example demonstrates how to use this method. This example is part of a larger example available in How to: Implement Communication Between Local Silverlight-Based Applications.
Imports System
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Messaging
Partial Public Class Sender
Inherits UserControl
Private messageSender As LocalMessageSender
Public Sub New()
InitializeComponent()
UpdateButton()
messageSender = New LocalMessageSender( _
"receiver", LocalMessageSender.Global)
AddHandler messageSender.SendCompleted, _
AddressOf sender_SendCompleted
SendMessage("message from Sender constructor")
End Sub
Private clickNumber As Integer = 1
Private Sub UpdateButton()
button.Content = "send message 'click " & clickNumber & "'"
End Sub
Private Sub Button_Click(ByVal sender As Object, _
ByVal e As RoutedEventArgs)
SendMessage("click " & clickNumber)
clickNumber += 1
UpdateButton()
End Sub
Private Const MAX_ATTEMPTS As Integer = 10000
Private attempt As Integer = 1
Private Sub SendMessage(ByVal message As String)
messageSender.SendAsync(message, attempt)
End Sub
Private Sub sender_SendCompleted(ByVal sender As Object, _
ByVal e As SendCompletedEventArgs)
If e.Error IsNot Nothing Then
LogError(e)
attempt += 1
If attempt > MAX_ATTEMPTS Then
output.Text = "Could not send message."
Return
End If
SendMessage(e.Message)
Return
End If
output.Text = _
"Message: " & e.Message & Environment.NewLine & _
"Attempt " & CType(e.UserState, Integer) & _
" completed." & Environment.NewLine & _
"Response: " & e.Response & Environment.NewLine & _
"ReceiverName: " & e.ReceiverName & Environment.NewLine & _
"ReceiverDomain: " & e.ReceiverDomain
' Reset attempt counter.
attempt = 1
End Sub
Private Sub LogError(ByVal e As SendCompletedEventArgs)
System.Diagnostics.Debug.WriteLine( _
"Attempt number {0}: {1}: {2}", CType(e.UserState, Integer), _
e.Error.GetType().ToString(), e.Error.Message)
End Sub
End Class
using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Messaging;
namespace SendingApplication
{
public partial class Sender : UserControl
{
private LocalMessageSender messageSender;
public Sender()
{
InitializeComponent();
UpdateButton();
messageSender = new LocalMessageSender(
"receiver", LocalMessageSender.Global);
messageSender.SendCompleted += sender_SendCompleted;
SendMessage("message from Sender constructor");
}
private int clickNumber = 1;
private void UpdateButton()
{
button.Content = "send message 'click " + clickNumber + "'";
}
private void Button_Click(object sender, RoutedEventArgs e)
{
SendMessage("click " + clickNumber);
clickNumber++;
UpdateButton();
}
private const int MAX_ATTEMPTS = 10000;
private int attempt = 1;
private void SendMessage(string message)
{
messageSender.SendAsync(message, attempt);
}
private void sender_SendCompleted(object sender, SendCompletedEventArgs e)
{
if (e.Error != null)
{
LogError(e);
attempt++;
if (attempt > MAX_ATTEMPTS)
{
output.Text = "Could not send message.";
return;
}
SendMessage(e.Message);
return;
}
output.Text =
"Message: " + e.Message + Environment.NewLine +
"Attempt " + (int)e.UserState +
" completed." + Environment.NewLine +
"Response: " + e.Response + Environment.NewLine +
"ReceiverName: " + e.ReceiverName + Environment.NewLine +
"ReceiverDomain: " + e.ReceiverDomain;
// Reset attempt counter.
attempt = 1;
}
private void LogError(SendCompletedEventArgs e)
{
System.Diagnostics.Debug.WriteLine(
"Attempt number {0}: {1}: {2}", (int)e.UserState,
e.Error.GetType().ToString(), e.Error.Message);
}
}
}
Version Information
Silverlight
Supported in: 5, 4, 3
Platforms
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.